Dual Route Theory of Reading

The dual route theory of reading, also known as the dual-route model of reading aloud, proposes that skilled readers use two separate cognitive pathways to convert written words into their spoken pronunciation. The lexical route allows a reader to recognize a familiar word as a whole by consulting an internal mental store of known words and their pronunciations, functioning much like an internal dictionary; this route correctly handles irregular, or exception, words whose pronunciation does not follow standard spelling-to-sound rules, such as colonel. The nonlexical, or sublexical, route allows a reader to sound out a word by breaking it into letters and letter groups and applying general knowledge of how those units correspond to sounds; this route works well for regularly spelled words and for unfamiliar nonwords but cannot correctly handle exceptions. The theory emerged in the early 1970s and was substantially developed through computational modeling by the researcher Max Coltheart, while researchers including John Marshall and Freda Newcombe documented patterns of acquired dyslexia, cases in which brain damage impairs one reading route while leaving the other comparatively intact, offering evidence that the two routes are at least partly separable in the brain. The theory remains widely used to explain both ordinary reading and patterns of reading difficulty and reading disorder.